Selective position push button switch



Nov. 5, 1963 K. w. ABENDROTH SELECTIVE POSITION PUSH BUTTON swrrdn 2 Sheets-Sheet 1 Filed Jan. 9, 1961 mv Ev INVE OR. K.W.ABENDFTOTH HlS ATTORNEY m 3 mm mm N ON 9 I mm m n o w t b mm 2 N O n M iv MN 9 Nov. 5, 1963 K. W. ABENDROTH 3,

SELECTIVE POSITION PUSH BUTTON SWITCH Filed Jan. 9, 1961 2 Sheets-Sheet 2 IN VEN TOR- K.W.ABENDROTH HIS ATTORNEY United States Patent 3,109,906 SELECTIVE POSITION PUSH BUTTON SWITCH Karl W. Abendroth, Rochester, N.Y., assignor to General Signal Corporation, a corporation of New York Filed Jan. 9, 1961, Ser. No. 81,493 3 Claims. (Cl. 200-87) This invention relates to electrical switch contactors of the push button type and more particularly relates to a push button switch which may be selectively positioned before and after manual operation.

Push buttons of the push-pull-turn type are commonly used on railway traffic control machines and the like for remotely controlling outlying switches, signals and the like. Usually with spring biased push buttons, the operator has to hold the push button in position until he receives a signal indication that the desired functions have been completed before permitting the push button to return to its original position. Non-spring biased types must be returned manually after the function has been completed, and as a result, are sometimes forgotten.

On modern day control machines the operator is required to perform several functions in sequence so that it is highly desirable to be able to remove his finger from the push button yet have the push button remain in its operated position until its function has been completed, after which it would be returned to normal automatically.

The present invention proposes a spring loaded push button switch which is provided with a permanent magnet holding means and is released at the proper time by means of energizing a coil winding with a polarity which opposes the holding flux of the permanent magnet and permits the biasing spring to return the push button switch to its original position. i

A modified form of the present invention proposes a push-turn button switch wherein push operation of the push button switch in its vertical center position employs the permanent magnet structure for holding it in its operated positions as described above. However, a push operation in either of its turned rotary positions will energize the coil winding to render the permanent magnet holding means inefiective, thus permitting the push button to return to its original position by reason of its spring bias immediately upon release by the operator.

More specifically, an armature is attached to the inner end of the push button plunger and magnetically cooperates with a permanent magnet which is associated with the core structure and the coil winding. The airgap between the permanent magnet and the armature is great enough and the magnetic flux force of the permanent magnet is small enough so that under normal conditions the magnetic attraction between the two is not great enough to overcome the spring bias of the push button plunger and cause operation of the plunger. when the push button plunger is depressed, the airgap is closed so that the plunger is held in its depressed position by themagnetic attraction between the permanent magnet and the armature.

Upon energization of the coil winding, flux of a proper polarity is created in the core structure which opposes the hold-ing flux of the permanent magnet, thus permitting the spring biased plunger to return the push button switch to its original normal position. Also, if desired for emergency purposes, the plunger may be pulled to its out position manually by exerting a pull of approximately one pound force on the push button as such a force would overcome the holding power of the permanent magnet.

The contact drum of the push button switch is universal in structure in that it is provided with longitudinal cylindrical grooves into which are inserted cylindrical bars However,

of metal or insulation as desired. Thus, various cont-act combinations can be made up for cooperation with the stationary contact fingers.

Other objects, purposes and characteristic features of the present invention will be apparent or pointed out as the description progresses with reference to the accompanying drawings wherein like reference characters will refer to like parts and in which:

FIG. 1 is a side elevation sectional view of the push button switch of the present invention and illustrated in a normal position wherein the armature is in a noncooperating position with respect to the permanent magnet and releasing core and coil structure;

FIG. 2 is a transverse sectional view through the shaft and mounting bushing of the push button switch of FIG. 1 as taken substantially on the line 2-2 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a transverse sectional view through the stationary contact mounting portion of the push button switch of FIG. 1 as taken substantially on the line 33 of FIG. 1 looking in direction of the arrows;

FIG. 4 is a transverse sectional view through the contact drum portion of the push button switch of FIG. 1 as taken substantially on the line 44 of FIG. 1 looking in the direction of the arrows;

FIG. 5 is a transverse sectional view through the casing portion of the push button switch of FIG. 1 as taken on the line 5-5 of FIG. 1 looking in the direction of the arrows and shows the permanent magnet, core and coil assembly mounted within the casing;

FIG. 6 is a back end view of the casing and terminal board portion of the push button switch of FIG. 1;

FIG. 7 is a side elevational view of the contact drum portion of the push button switch of FIG. 1;

FIG. 8 is a side elevational sectional view of a modiiied form of the push button switch of the present invention shown in FIG. 1, the modification comprising a means whereby the push button has three radial push positions of which the center one is the only one eiiective to be held by the permanent magnet;

FIG. 9- is a transverse sectional view through the shaft and the mounting bushing of the push button switch of FIG. 8 as taken on the line 9-41 of FIG. 8 looking in the direction of the arrows and shows the three radial positions which the push button shaft can assume;

FIG. 10 is a transverse sectional view through the casing portion of the push but-ton switch of FIG. 8 as taken on the line 10 10 of FIG. 8 looking in the direction of the arrows and shows the three radial detents for positioning the push button shaft in each of its three posi tions;

FIG. 11 is a transverse sectional view through the contact drum portion of the push button switch of FIG. 8 as taken on the line 1111 of FIG. 8 looking in the direction of the arrows and shows the modified contact arrangement;

FIG. 12 is a diagrammatic explanatory view of the' push button switch of FIG. 8 with the contact drum and stationary contacts shown in developed form to illustrate the operation thereof; and

FIGS. 13 and 14 are diagrammatic views of the permanent magnet holding means shown to illustrate the direction of flux movements through the permanent magnet and the core structure in both the energized and deenergized conditions of the coil winding.

Referring now to the single position form of the push button switch of the present invention as shown in FIGS. 1 to 7 inclusive, the push button switch as a whole is shown conveniently mounted on a control panel 15 of insulation board or other suitable material. The panel 15 is provided with a shouldered opening 16 into which the threaded end portion of the push button housing 17 extends. The housing 17 is of insulation or other suitable material and is substantially cylindrical in shape with both its threaded end portion and its contact end portion having a smaller diameter than the central portion, thus forming shoulders thereon.

in assembly, a ring piece 18 is placed over the threaded end portion of the housing 17 and lies between the back surface of the panel and the shouldered portion of the housing 17. A cap nut 19 inserted from the front surface of the panel 15 is threaded onto the threaded end portion of the housing 17, thus clamping the housing 17 and the ring 18 to the panel 15. A pin 20 extending through the ring 18 into the panel 15 prevents the ring 13 from turning whereas a nub or key 21 on the housing 17 extends into a keyway slot 22 in the ring 18 to prevent the housing 17 from turning.

The push button plunger rod or shaft 23 is preferably made of nylon, stainless steel or other hard material and is slidably mounted Within bearing surfaces formed on the inside of both ends of the housing member 17. A pin 24 extending radially from the plunger rod 23 into a keyway groove 25 formed on the inside of the housing member 17 permits longitudinal movement of the plunger rod 23 but prevents turning thereof. The plunger rod 23 is spring "loaded by means of a coil spring 26 which surrounds the small diameter portion of the plunger rod 23 and is disposed between a shoulder on the plunger rod 23 and a shoulder on the inside of the housing member 17, thus, the plunger rod 23 is normally spring biased to an outward position wherein the pin 24 bears against a nylon washer 27 lying within the cap nut 19.

The plunger rod 23 is provided with a knob 28 at its outer end and a contact drum 29 of insulation material at its inner end. The contact drum 29 is cylindrical in shape and is provided with tour longitudinal circular grooves which are located near its outer periphery and spaced ninety degrees apart as clearly shown in FIGS. 1 and 4. Combinations of metallic rods 30 and insulation rods 3-1 are inserted in these grooves to make up contact combinations as desired. As noted, these rods 30 and 31 have an outer periphery which extends outside of the outer periphery of the contact drum 29 so that they can cooperate with the various pairs of stationary contact fingers 32.

In assembly, the contact drum 29 is provided with a shouldered head portion 33 which acts as a limit to position the rods 30 and 31. This shouldered head portion 33 is also provided with a key rib 34 which seats in a cross slot keyway formed in the inner end of the push button plunger 23. The contact drum is then fastened to the end of the push button plunger by means of a bolt 35 which passes through the contact drum 29 and is threaded into the end of the push button plunger 23 (see FIG. 1). An insulation washer 36 located under the head of the bolt 35 holds the contact and insulation rods 39 and 31 in position within their respective grooves when the bolt 35- is tightened down, and the contact drum 29 is prevented from turning by reason of the key 34 seated in the keyway.

The various pairs of stationary con-tact fingers 32 are mounted ninety degrees apart around the outer periphery of the inner end of the cylindrical housing member 17 as clearly shown in FIGS. 1, 3 and 4. Screws 37, which p assthrough alternately spaced insulation washers 38 and the contact fingers 32, are threaded into the housing 17 and tightened down to hold the contact fingers 32 in position. Insulation bushings 39, around the screws 37 prevent electrical contact between the metallic screws 37 and the metallic contact fingers 32.

From the description above given thus far of the push button switch it can be seen and readily understood that a push movement against the knob 28 :ofthe spring loaded plunger 23- will cause an inward movement of the contact drum 29 to a position wherein each pair of stationary contacts 32 (see FIG. 1) will have one contact finger 32 resting on an insulation rod 31 whereas its other contact finger 32 will be resting on a metallic nod 30. Thus, the normally closed circuit between each of the two contact fingers 32 and its associated metallic contact rod 30 is broken. As soon as the push button knob 28 is released, the compressed spring 26 would return the push button plunger 23 and its associated contact drum 29 to its normal position with the stop pin 24 hearing against the cushioning washer 27, thus again closing a circuit through the two contact fingers 32 and the metallic rod 30. The push button plunger 23 is held in vertical alignment during its movement by reason of the stop pin 24 riding in the keyway groove 25.

As previously mentioned, various contact combinations may be made up by placing the insulation rods 31 and the metallic rods 30 in their grooves in different sequence. As shown in FIG. 7, the combination is such that normally two circuits are made up (see FIGS. 1 and 4),

whereas the other two circuits are broken as each set of 7 contact fingers 32 would rest one on a metallic rod 30 and one on an insulation rod 31.

Referring now to the permanent magnet holding means for the push button rod 23 of the present invention, the head of the bolt 35 is provided with an extension piece 40 on which is loosely mounted a circular shape flat arnrature 41. The armature 41 is provided with a flange portion 42 and a hole therethrough large enough to form a loose fit over the extension piece 40'. -A crosspin 43 holds the armature 41 on the extension piece 40, the looseness of the joint permitting the armature 41 to wobble on the end of the extension piece 40 for reasons explained cylindrical shaped housing 45 which extends beyond the armature 41 and houses a permanent magnet 46, a core structure 47, a coil winding 48 and a terminal board 49. This housing 45 is provided with two oppositely disposed openings 50 in its side walls to permit access to the contact fingers 32 and the like, as shown more clearly in FIGS. 3 and 4.

The permanent magnet 46 is a hollow cylinder and seats against the flat disc portion of the core piece 47, a leg portion 47A of the core piece extending Within the permanent magnet 46. This two piece assembly is mounted within the cylindrical housing 45 and held in place by means of bent-in punch out lugs 51 in the housing 45, which lugs fit into grooves provided in the magnet 46 and core piece 47. The coil winding 48 fits over the leg portion 47A of the core piece 47 and lies within the cylindrical shaped permanent magnet 46. The coil winding 48 is held in position by means of a split ring washer 52 mounted on the end of the core leg 47A.

The terminal board 49 is also disc shaped and is mounted within the open end portion of the cylindrical housing 45 and held in position by bent in punch out lugs 53 in the housing 45. Suitable terminal posts 54 are provided on the terminal board 49 to which the wire leads 55 of the coil winding 48 are attached to facilitate external connections thereto.

Referring again to the permanent magnet holding means for the switch plunger rod 23, the permanent magnet-core structure assembly 46-47 is such that with no energy on the coil winding 48, the permanent magnet flux is induced into the core 47 and its leg 47A in such a manner as to cause an attraction thereto of the armature 41 through i cause of the opposing spring bias produced by the spring 26 acting on the plunger rod 23'.

However, upon a push movement to operate the switch plunger rod 23 and its associated contacts 30 32, the spring 26 is depressed and the armature 41 will practically come into contact with the permanent magnet-core structure 4647 as diagrammatically illustrated in FIG. .13 and the magnetic attraction therebetween will be great enough to hold the plunger rod 23 in its depressed position. In this connection it should be mentioned that the contacting side of the armature 41 is provided with an insulated covering piece 56 which acts as a residual and prevents actual contact between the armature 41 and the permanent magnet-core structure 4647. Also, as the armature 41 is loosely mounted on the free end of the rod 23 may be depressed to operate the contact dnnn 29, the key pin 24 sliding along in the center keyway groove 60. By turning the push button knob 28 to the right (clockwise), the detent pin 66 will ride out of the detent groove 63 against the bias of the spring 26 and into the detent groove 65 (see FIGS. 9 and 10). In this position the key pin 24 will line up with the keyway groove 61 and the push button plunger rod 23 may be depressed to again operate the contact drum 29 in its turned position, thus plunger rod 23 as previously described, the armature is permitted to square up to the core structure regardless of its horizontal mounting alignment.

Thus it can be seen and understood that once the push button plunger rod 23 is depressed to operate its associated contacts 30-32, it will remain held in such depressed position until it is magnetically released or forceably released.

Y The push button plunger rod 23 may be magnetically released by energization of the coil Winding 48. Such energization of the coil Winding 48 is usually accomplished automatically by an indication circuit initiated upon completion of the function for which the switch was operated, but it should be understood that any manner of energization of the coil winding 48 would sufiice'. Upon energization of the coil winding 48, the flux produced thereby would oppose the permanent magnet flux, thus causing diminution of the magnetic attraction between the armature 41 and the permanent magnet-core structure 4647 and permitting the biasing spring 26 to return the switch plunger rod 23 to its normal position.

As shown diagrammatically in FIG. 14, with the contact 57 of the indication relay R closed, the winding 48 is energized and the flux path induced into the leg 47A of the core structure 47 is reverse to and in opposition to the flux path created by the permanent magnet 46. With the polarities and the flux flow paths thus in opposit on to each other as indicated by the legends N and S and the arrows in dotted and full lines, there is insufiicient magnetic attraction to hold the armature 41.

In actual practice, the holding power of the permanent magnet attraction is equal to about one pound of force, so that, in case of emergency or otherwise, a one pound force pull on the push button knob 28 would break the holding attraction between the armature 41 and the permanent magnet-core structure 46--47 and return the switch plunger rod 23 to its normal position, wherein it would beheld by the bias of the spring 26.

Referring now to the form of the present invention as shown in FIGS. 8 to 12 inclusive which incorporates a turn feature in the push button assembly, the basic consetting up a'different contact combination. Similarly, by turning the push button knob 28 to the left (counterclockwise) the detent pin 66 will engage the detent groove 64 and position the key pin 24 in line with the keyway groove 62 so that the push button plunger rod 23 may again be depressed to operate the contact drum 29.

As previously mentioned, this form of push-turn switch may have its contact drum contacts assembled in various manners to perform functions as illustrated in developed form in FIG. 12. One of the functions contemplated and herein shown is to have the permanent magnet 46 effective to hold the armature 41 when the switch is operated in its center position but to have the permanent magnet 46 rendered ineffective to hold the armature 41 when the switch is operated in either of its right or left turned positions. This function is accomplished by providing a means to energize the coil winding 48 when the switch is operated in either of its right or left turned positions.

Such means is provided in the contact make up of the contact drum 29 as shown in FIG. 12. The grooves '1 and 5 are filled with a full length insulation rod 31 and when in a normal position as shown, the circuits between their respective cooperating contact fingers 32m and 32:: are broken. The grooves '3 and 7 are filled with long metallic rods 30 and short insulation rods 31 so that the struction is similar to that already shown and described and the same reference characters are used where possible and the new structure only will be specifically described.

60, 61 and 6-2 to receive the pin 24 in its center, right or left hand positions, as shown in FIG. 9. Also, the push button housing 17 is provided at its inner end with three detent grooves 63, 64 and 65 to accommodate a pin 66 which also protrudes from the plunger rod 23 and serves to hold the plunger rod in either of its three positions, as shown in FIG. 10. Also, the contact drum- 29 is provided with eight longitudinal circular grooves to receive the metallic rods 30 and the insulation rods 31 to make up certain contact combinations as illustrated in FIGS. 11 and 12 and explained hereinafter.

With particular reference to FIGS. 8, 9 and 10, it can be seen that the push button plunger rod 23 is normally circuits between their respective cooperating contact fingers 32c and 323 are made in one case and broken in the other, depending on the location of the metallic rods 30.

It can now be seen that if the push button rod 23- were depressed with the switch in its normal positions as shown,

the circuit between the contact fingers 32c would be broken and the circuit between the contact fingers 32g would be made up. Also, as the contacts 32e are riding on a full length insulation rod 31, the circuit for energizing the coil winding 48 would remain broken and the armature 41 would become attracted to the permanent magnet-core structure 46-47 and the push button rOd 23- would remain in its depressed position. However, as previously described, the push button rod 23 would be released upon closure of the contact 5 7 of the indication relay R when the function had been completed, due to the energization of the coil winding 48. Assuming now that the push button knob 28 was turned to the right before the push button rod '23 was depressed as described above, it can be seen that the metallic rod 30 located in the groove 4 of the contact drum 29 would bridge the contact fingers 322,

.thus closing the circuit to the coil winding 48 and causing it to be energized. As previously described, energization of the coil winding '48 creates a flux flow which opposes the permanent magnet flux flow, thus rendering the core structure incapable of attracting the armature 41. Under such conditions, the push button rod 23 would return to its normal outward position when released due to the bias of the spring 26.

Similarly, if the push button knob 28 should be turned to the left before the push button rod 23 was depressed, the metallic rod 30 located in the groove 6 of the contact drum 29 would bridge the contact fingers 32a, thus energizing the coil winding 48 and rendering the permanent magnet 46 incapable of holding the armature 4 1.

From the foregoing description and with reference to the drawings, it should be seen and understood that the present invention provides a push button operating means wherein the push button plunger may be effectively magnetically held in itsoperated position for a predetermined time after which it is automatically electrically released and returned to its original position by a spring biasing means. Furthermore, means are provided to render the permanent magnet holding means ineifective in certain operating positions of the push button plunger. Also, the push button plunger may be returned to its normal position if necessary by exerting a pulling force on the push button knob to the extent required to overcome the holding power of the permanent magnet. Under normal conditions the biasing spring maintains the push button plunger in its normal position and the attracting force of permanent magnet is insufficient to over the spring bias due to the large airgap maintained between the armature and the permanent magnet.

Having shown and described two forms which the present invention can assume and the mode of operation thereof, it should be understood that various other forms and modifications could be made therein, all without departing from the spirit of the invention within the scope of the appending claims.

What I claim is:

'1. In a push button switch contactor having a plunger rod mounted within a cylindrical housing and a contact drum attached to said plunger trod, a coil spring positioned to bias said plunger rod'to an outward position, stationary contacts cooperating with said contact drum, an armature when positioned in its other longitudinal groove positions will condition certain other stationary contacts and permit said coil spring to return said plunger rod to its outward position immediately upon release.

2. A push button switch contactor having a plunger rod with a contact drum attached thereto, said contact attached to the free end of said plunger rod, a permanent magnet, a core structure and a coil winding mounted for magnetic cooperation with said armature, a plurality of spaced longitudinal grooves in one end of said housing and a first radial extending pin in said plunger rod for cooperation with said grooves, a plurality of spaced detents in the other end .of said housing and a second radial extending pin in said plunger rod for cooperation with said detents, means for energizing said coil winding to render said permanent magnet ineffective in accordance with certain predetermined positions of said plunger rod; whereby depression of said plunger rod in its center longitudinal groove position will condition certain of said stationary contacts and permit said permanent magnet to hold said armature against the bias of said coil spring for a predetermined time whereas depression o-f said plunger rod,

drum including :at least one longitudinal groove, a rod inserted in said groove, said rod being formed with predetermined conducting and insulating areas, stationary contactor circuit connectors mounted in registry with said rod, a coil spring positioned to bias said plunger rod to a first position effective to maintain said stationary contactors in registry with a selected region of said rod on said contact drum, an armature attached to the free end of said plunger rod, a permanent magnet suitably disposed to magnetically cooperate with said armature whenever said plunger rod is manually deprmsed to a second position to hold said plunger rod in said second position effective to maintain said stationary contactors in registry with a second selected region of said rod on said contact drum, a coil and core structure suitably disposed adjacent said permanent magnet and means for at times energizing said coil winding to render said permanent magnet ineffective permitting said coil spring to bias said plunger to said first position.

3. The invention as claimed in claim 2 wherein said' plunger rod is mounted within a cylindrical housing having a longitudinalgroove formed in said housing and a pin mounted in said plunger rod extending radially into registry with said longitudinal groove effective to permit only longitudinal movement of said plunger rod thereby maintaining said stationary contactor circuit connectors and said rod on said contact drum in alignment.

References Cited in the file of this patent UNITED STATES PATENTS 2,298,068 Pierce Oct. 6, 1942 2,441,888 Landing May 18, 1948 2,447,632 Bush Aug. 24, 1948 

1. IN A PUSH BUTTON SWITCH CONTACTOR HAVING A PLUNGER ROD MOUNTED WITHIN A CYLINDRICAL HOUSING AND A CONTACT DRUM ATTACHED TO SAID PLUNGER ROD, A COIL SPRING POSITIONED TO BIAS SAID PLUNGER ROD TO AN OUTWARD POSITION, STATIONARY CONTACTS COOPERATING WITH SAID CONTACT DRUM, AN ARMATURE ATTACHED TO THE FREE END OF SAID PLUNGER ROD, A PERMANENT MAGNET, A CORE STRUCTURE AND A COIL WINDING MOUNTED FOR MAGNETIC COOPERATION WITH SAID ARMATURE, A PLURALITY OF SPACED LONGITUDINAL GROOVES IN ONE END OF SAID HOUSING AND A FIRST RADIAL EXTENDING PIN IN SAID PLUNGER ROD FOR COOPERATION WITH SAID GROOVES, A PLURALITY OF SPACED DETENTS IN THE OTHER END OF SAID HOUSING AND A SECOND RADIAL EXTENDING PIN IN SAID PLUNGER ROD FOR COOPERATION WITH SAID DETENTS, MEANS FOR ENERGIZING SAID COIL WINDING TO RENDER SAID PERMANENT MAGNET INEFFECTIVE IN ACCORDANCE WITH CERTAIN PREDETERMINED POSITIONS OF SAID PLUNGER ROD; WHEREBY DEPRESSION OF SAID PLUNGER ROD IN ITS CENTER LONGITUDINAL GROOVE POSITION WILL CONDITION CERTAIN OF SAID STATIONARY CONTACTS AND PERMIT SAID PERMANENT MAGNET TO HOLD SAID ARMATURE AGAINST THE BIAS OF SAID COIL SPRING FOR A PREDETERMINED TIME WHEREAS DEPRESSION OF SAID PLUNGER ROD WHEN POSITIONED IN ITS OTHER LONGITUDINAL GROOVE POSITIONS WILL CONDITION CERTAIN OTHER STATIONARY CONTACTS AND PERMIT SAID COIL SPRING TO RETURN SAID PLUNGER ROD TO ITS OUTWARD POSITION IMMEDIATELY UPON RELEASE. 